The micronization process for mineral powders involves reducing particle size to the micron or sub-micron range (typically 1–100 µm) to enhance properties like surface area, reactivity, and dispersibility. This is widely used in industries such as pharmaceuticals, cosmetics, ceramics, and coatings.
Key Micronization Techniques for Mineral Powders
1. Jet Milling (Fluid Energy Milling)
– Uses high-pressure gas (air or nitrogen) to collide particles at high velocities.
– Achieves fine powders (1–50 µm) with narrow particle size distribution.
– Suitable for heat-sensitive minerals (e.g., talc, calcium carbonate).
2. Ball Milling
– A rotating drum with grinding media (steel/ceramic balls) crushes minerals via impact and attrition.
– Can achieve sub-micron sizes with prolonged milling.
– Used for hard minerals like quartz and zirconia.
3. Attrition Milling
– Similar to ball milling but uses smaller grinding media and higher shear forces.
– Effective for ultrafine grinding (<10 µm).
4. Planetary Milling
– High-energy milling where jars rotate around a central axis while spinning on their own axis.
– Produces nano-sized particles (<1 µm) for advanced applications.
5. Wet Grinding & Media Milling
– Uses liquid suspension (water or solvents) with beads to prevent agglomeration.
– Ideal for ultra-fine and nano-minerals (e.g., kaolin, barite).
6. Cryogenic Grinding
– Minerals are cooled with liquid nitrogen (-196°C) before milling to prevent heat degradation.
– Used for soft or elastic minerals (e.g., sulfur, mica).
Factors Influencing Micronization
– Mineral Hardness (Mohs scale determines grinding method).
– Moisture Content (wet vs. dry milling choice).
– Desired Particle Size & Distribution.
– Thermal Sensitivity (avoid degradation in heat-generating processes).
.jpg)
Applications of Micronized Mineral Powders
– Paints & Coatings: Improved opacity and dispersion (TiO₂, CaCO₃).
– Pharmaceuticals: Better bioavailability (talc, silica).
– Cosmetics: Smooth texture in powders